Given that the two kinases are essential for proximal events in signal transduction in all T cells (αβ, γδ, NKT cells) this simple mechanism of regulating Zap70 expression by Lck may regulate TCR signaling in developing thymocytes in response to selecting ligands critical for production of mature T cells devoid of autoimmunity and in mature T cells in response to self or foreign peptide. This evidence concerns the gene LCK and Autoimmunity.